The incident occurred at the AS Tower in Bhaluka’s Jamirdia Mastarbari area around 12:30am on Sunday.
“The blast destroyed everything,” Mymensingh Superintendent of Police Syed Nurul Islam told bdnews24.com. “It could be a bomb or a gas cylinder explosion. We have been unable to confirm the cause.”
A bomb disposal unit from Dhaka had arrived and begun work, he said.
“Perhaps we will learn the cause of the blast after they have completed their work.”
According to police and locals, all four are students at the Khulna University of Engineering and Technology. They rented a flat on the third floor of AS Tower on Mar 10 to intern at a textile mill in Bhaluka.
Abdur Razzak, who owns the newly constructed building, runs a clothing business and lives in Dhaka. He is being questioned, RAB-14 Captain Lt Col Shariful Islam told bdnews24.com.